You understand correctly,
@faberryman , but film that has been removed from the sealed pouch, in my experience, is more prone to mottling and wrapper offset than film still sealed (even when stored together over the same time frame). Therefore, again based on my experience, I'd be reluctant to purchase respooled 620 film (and in truth, to pay someone else, nearly doubling the price of each roll, to do what I can do myself -- I've got a good supply of old metal 620 spools, dark bag, and darkroom) for film I might not use immediately. My guess would be up to six months is likely to be okay, but where sealed film is usually good for a decade (or much more) past expiration, film that's been unsealed (even when stored in an airtight film can) is not.
Additionally, at least the FPP 620 spools are injection molded plastic, and as such have slightly thicker flanges than the old metal ones, which means there are a (very) few 620 cameras that don't like them. Some of the 620 I've seen also seems to have drive key slots compatible with 120, which will make them loose on a 620 drive key, potentially leading to jams if there's too much friction in the film path.
I don't expect we'll ever see metal 620 spools again; they'd cost too much to make in the quantities demanded (as opposed to tens or hundreds of millions a year when Kodak was selling most of their medium format films in 620). It's tempting to wonder, however, about a hybrid, with stamped metal end flanges bonded to a plastic core (which could be thicker than the original 620 core, as witness trimmed 120 meeting diameter limits without respooling).